The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC design and material have produced generations of ICs where each generation has smaller and more complex circuits than previous generations. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased.
In small generations, since device size is getting smaller and transistor density is getting higher, the interconnection of metal to metal gate (MG), and metal to active area (MD) by a via becomes more critical. Improvement is desired in this area.